The present invention relates in general to fasteners and more particularly to an apparatus and method for installing a threaded fastener having a sleeved or interference fit into a workpiece.
Threaded fasteners having a sleeved or interference fit are widely used in several applications including automobile, aircraft and general machinery. Typically, these fasteners are installed into a workpiece thereby enabling one or more other structures to be attached to the workpiece. The type of workpiece depends on the application, and may, for example, include a stringer in an aircraft or a suspension beam in an automobile.
Installation generally involves seating the fastener in the workpiece. Seating commonly means that the fastener is frictionally fitted in the workpiece such that the fastener will not dislodge. In other words, the frictional or contact area between the surface of the workpiece and the fastener is enough to keep the fastener securely in the workpiece. One way to identify when the fastener is seated in the workpiece is when the fastener is installed far enough into the workpiece that the flanged head on one end of the fastener contacts the workpiece.
Typically, a great deal of force is required to install the fastener into the workpiece. Most fasteners, therefore, are installed into the workpiece either by pressing or by hammering. Although both of these methods provide the necessary force required, several problems exist.
One problem with pressing the fastener into the workpiece is that the fastener can easily become off-center. This can lead to incorrect installation of the fastener or, even worse, bending of the fastener. Because fastener installation usually occurs on a production line, this can lead to production delays and increased production costs.
One problem with hammering the fastener into the workpiece is that this method develops the needed force by high impact with the fastener. This high impact can do great damage to the fastener and workpiece and cause them to bend, crack or even break. Moreover, these anomalies may not be noticed during production and may lead to premature failure of the fastener.
Therefore, what is needed is an apparatus and a method for installing a fastener into a workpiece that can supply the necessary force without high impact. Furthermore, the apparatus and method should be able to install the fastener reliably and safely without the danger of bending, cracking or breaking the fastener or workpiece. The safety and reliability of this apparatus and method would increase yield and quality, decrease production time and thereby decrease production costs.
Whatever the merits of the aforementioned tools and methods for installing fasteners, they do not achieve the benefits of the present invention.
To overcome the limitations in the prior art as described above and other limitations that will become apparent upon reading and understanding the present specification, the present invention includes an apparatus and method for installing a threaded fastener having a sleeved or interference fit into a workpiece. The present invention is capable of reliably and safely installing a fastener in a workpiece without damage to either the fastener or workpiece. Furthermore, the safe and reliable way in which the invention installs a fastener can have a beneficial effect on the production process.
The apparatus of the present invention includes a pulling device for pulling a fastener into the workpiece, an adapter for connecting the fastener and the pulling device and a collar that fits over the adapter for allowing the adapter to move inside the collar when subject to a pull from the pulling device.
The apparatus of the present invention may also be implemented as a method of installing a threaded fastener having a sleeved or interference fit into a workpiece. This method includes inserting a fastener, threaded end first, into a hole in the workpiece until the threads are exposed on the other side of the workpiece. Next, an adapter is attached to the threaded portion of the fastener and a collar is placed over the adapter. A pulling device is then attached to the other end of the adapter. When the pulling device applies enough pressure, the fastener is pulled into the workpiece until it is fully seated.
Other aspects and advantages of the present invention as well as a more complete understanding thereof will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the invention. Moreover, it is intended that the scope of the invention be limited by the claims and not the preceding summary or the following detailed description.